Advances in microelectronics have enabled a new generation of scalable sensor networks. Combining sensing, signal conditioning, digital processing, data logging, and wireless digital communications into smaller and smaller integrated circuits allows nodes of these networks to be embedded more and more deeply into machines and structures. But powering such wireless sensor nodes for the long term remains a challenge in many applications, and the more deeply these nodes are embedded, the more challenging it becomes to find ways to maintain a charge on their energy storage elements.
Energy harvesting, or scavenging ambient energies from the operational environment, represents an exciting way to automatically store energy and eliminate battery maintenance. However, in many applications, the source of ambient energy may be intermittent, the kinds of energy that can most easily be harvested may also change with the environmental conditions, and the range of voltages. In addition, the range of voltages provided may vary. Thus, a better solution is needed, and this solution is provided by the present patent application.